As ceramic materials for use in multilayer ceramic capacitors, conventionally, barium titanate based compounds which have a high dielectric constant have been widely known.
In addition, this type of multilayer ceramic capacitor has a ceramic sintered body obtained by alternately staking dielectric layers composed of a dielectric ceramic and internal electrode layers and applying a firing treatment, and has external electrodes formed on both ends of the ceramic sintered body.
Further, with the development of electronics technology in recent years, the reduction in size and the increase in capacitance have been rapidly progressed for multilayer ceramic capacitors, and accordingly, dielectric layers and internal electrode layers have been also reduced in thickness, and increased in the number of layers.
However, when the dielectric layers and the internal electrode layers are reduced in thickness and increased in the number of layers as just described above, the coverage of the internal electrode layers on the dielectric layers is decreased due to deformations during stacking, the difference in shrinkage behavior during firing, etc., thereby generating electrode defects in the internal electrode layers, and for this reason, there is a possibility of causing a decrease in electrostatic capacitance or a variation in electrostatic capacitance.
Therefore, for example, Patent Document 1 proposes a multilayer ceramic capacitor including external electrodes on end surfaces of a capacitor main body of alternately laminated dielectric layers containing barium titanate as their main constituent and internal electrode layers containing Ni as its main constituent, where the number of vacancies per unit area of periphery in the internal electrode layers is smaller than the number of vacancies per unit area of the central part excluding the periphery.
In Patent Document 1, the number of vacancies per unit area at the periphery of the internal electrode layers excluding connecting ends thereof to the external electrodes is made smaller than the number of vacancies per unit area of the central part excluding the periphery of the internal electrode layers, thereby reducing defects around the internal electrode layers, and thus trying to keep a decrease or variation in electrostatic capacitance from being caused, even when the dielectric layers and internal electrodes are reduced in thickness and increased in the number of layers.
Patent Document 1: Japanese Patent Application Laid-Open No. 2008-85041 (claim 1, paragraph numbers [0009], [0045] to [0052], etc.)